Chapter 7: Carbohydrates

carbonyl group

a carbon double bonded to an oxygen

aldehyde

molecule containing the carbonyl group at the end of the carbon chain

ketone

molecule containing the functional group on an internal carbon

aldose

sugar with its carbonyl group on the outside

ketose

a sugar with a carbonyl group in the middle of other carbons

stereoisomers

molecules with the same formula but different structures

D-isomers

in humans, the most common stereoisomer of sugars

glycolysis

the conversion of glucose to energy, CO2, and H2O; immediate energy

glycogenesis

the conversion of glucose to glycogen; occurs when immediate energy is not required

liver

storage location for glycogen

glycogenolysis

breakdown of glycogen into glucose to be used as energy

lipogenesis

conversion of glycose to adipose tissue; occurs when immediate energy is not needed and glycogen stores are full

lipolysis

the breakdown of fat to use as energy; after glycolysis stores are depleted

gluconeogenesis

the formation of glucose from keto acids, amino acids, and protein

insulin

hormone that decreases the overall level of blood glucose; increases glycolysis, glycogenesis, and lipogenesis while decreasing glycogenolysis and gluconeogenesis

Beta cells of the islets of Langerhans

cells within the pancreas that produce insulin

glucagon

increases overall level of blood glucose between meals and during other fasting times; promote glycogenolysis, gluconeogenesis, and lipolysis; decreases glycolysis, glycogenesis, and lipogenesis

alpha cells of the islets of Langerhans

cells in the pancreas that secrete glucagon

hypoglycemic agents

decrease blood glucose; only one is insulin

hyperglycemic agents

increase blood glucose levels; glucagon, epinephrine, cortisol, ACTH, and growth hormone; thyroxine, triidothyronine

endogenous insulin

proinsulin is converted to insulin by cleaving C-peptide

exogenous insulin

insulin produced outside the body; already active and does not contain C-peptide

Diabetes Mellitus (DM)

a group of diseases characterized by hyperglycemia due to defects in insulin production, action, or both; seventh leading cause of death in the U.S. and primary cause of blindness and renal disease

Type 1 diabetes mellitus

insulin-dependent diabetes mellitus (IDDM); autoimmune disease in which immune cells destroy the beta cells in the islets of Langerhans; leads to insulinopenia

symptoms of Type 1 diabetes

polydipsia (excessive thirst), polyuria (excessive urination), polyphagia (increased appetite), rapid weight loss, blurred vision, mental confusion, and dehydration

5-10% of total DM cases

Type 1

diabetic ketoacidosis

lack of insulin leads to an excess of glucagon; increases fat and muscle breakdown, which leads to buildup of ketones in the blood

Type 2 Diabetes Mellitus

characterized by insulin resistance; not immune mediated, has a strong genetic predisposition, has a gradual onset, is not insulin-dependent, and not ketosis prone

90-95% of total DM cases

Type 2

gestational diabetes

DM associated with pregnancy; occurs in 1-5% of pregnancies and is usually diagnosed during regular screenings for blood glucose levels

secondary diabetes

DM secondary to other conditions, such as pancreatic disease, endocrinopathies, drugs/chemicals, and genetic syndromes

complications of diabetes include

cerebrovascular disease, permanent kidney damage, diabetic foot infections, peripheral neuropathy, heart attack, retinopathy and blindness

Normal FPG level

70-99 mg/dL

Prediabetic/impaired fasting glucose FPG

100-125 mg/dL

Diabetes mellitus FPG

>126 mg/dL

Normal OGTT

<140 mg/dL

Prediabetes/impaired glucose tolerance OGTT

140-199 mg/dL

provisional diabetes mellitus OGTT

>200 mg/dL